Tap Tool Geometry for Fast Withdrawal and Thread Accuracy
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Solution Overview
Problem
Existing tap tools experience bending stress and reduced dimensional accuracy due to cutting resistance, leading to increased machining time and limited effectiveness in synchronous tap machining.
Innovation Solution
A tap tool design with a thread section, pad sections, and a non-engagement section that allows simultaneous release of engagement with the threaded groove, enabling high-speed withdrawal without rotation, supported by the screw hole via pad sections to minimize cutting resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the outer diameter of the tap tool is made smaller than the inner diameter of the screw hole, then the tap tool can be used for tap machining, but bending stress based on cutting resistance is generated and dimensional accuracy is reduced
Solution Approach 1:
The tap tool is divided into distinct functional sections: a thread section with blade sections for cutting, pad sections for support, and a non-engagement section. This segmentation allows each part to perform its specific function - the blade sections machine the threaded groove while the pad sections provide support to reduce bending stress and deflection.
Solution Approach 2:
The pad sections act as intermediary elements between the thread section and the screw hole. These pad sections engage with the threaded groove to provide support and reduce cutting resistance, thereby minimizing deflection and maintaining dimensional accuracy during the machining process.
2Device complexity
If conventional tap tools are used with one tip for tap machining, then the structure is simple, but the tap machining time increases when compared to tools designed for simultaneous pilot hole and tap machining
Solution Approach 1:
The tap tool is designed with multi-functionality to perform both pilot hole machining and tap machining operations. The tool includes blade sections for cutting threaded grooves and pad sections for support, enabling it to efficiently machine both the pilot hole and the screw hole in sequence without requiring tool changes.
3Extent of automation
If synchronous tap machining is performed with rotation and linear feeding synchronized, then the machining process is controlled, but the withdrawal time is substantially equal to the machining time
Solution Approach 1:
The tap tool employs dynamic operation modes: during machining, the tool rotates and feeds synchronously to machine the threaded groove; after machining, the tool shifts in a direction orthogonal to the axis of rotation to release engagement, enabling rapid withdrawal without rotation. This dynamic switching between operational states optimizes the total cycle time.
4Length of moving object
If the tap tool is elongate to reach deep screw holes, then the tool can machine deep holes, but deflection increases and dimensional accuracy is reduced
Solution Approach 1:
The pad sections serve as intermediary support elements that engage with the threaded groove during machining. This support mechanism reduces cutting resistance and prevents deflection in elongate tap tools, enabling them to maintain dimensional accuracy even when reaching deep screw holes.
Solution Approach 2:
The invention changes the operational parameters by introducing a shift movement orthogonal to the axis of rotation after machining. This parameter change allows the tool to release engagement with the threaded groove and withdraw rapidly, reducing the overall cycle time while maintaining accuracy during the machining phase.
Data Source
AI summary
The tap tool (10) has an axis of rotation (Cr) and machines a pilot hole (6′) so that the same becomes a screw hole (6) in a state where the axis of rotation has been matched to a central axis (C6) of the pilot hole which is provided to a workpiece, wherein the tap tool (10) is characterized by being provided with: a thread section (14) having a blade section (14a) for machining a thread groove of the screw hole; pad sections (15, 16) located behind in a direction of rotation of the blade section, and engaging with the thread groove machined by the blade section during the machining of the thread groove; and a non-engagement section (17) for forming a space (20) between said section and the screw hole in a cross-sectional view where the axis of rotation and the central axis of the screw hole have been matched. The space has a size that enables simultaneous release of the engagement between the thread section and the thread groove and the engagement of the pad sections and the thread groove, in a case where the tap tool has shifted in a direction orthogonal to the axis of rotation within the screw hole, such shift being from the state where the axis of rotation and the central axis of the screw hole have been matched.